Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Oct Tue 20, 2020 11:16 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 205 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6 ... 11  Next
Author Message
 Post subject:
PostPosted: Apr Thu 07, 2011 9:10 pm 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
Tom Schulz wrote:
That might not work correctly.

You know what - I'll bet you're right. I only did a static test on it, manually connecting the S & R inputs high and low and observing the outputs. That's no guarantee the ~Q output is even usable in the circuit. Although I suppose I could solder it back in and see if I'm getting a square wave there.

For the moment though, I'm still hoping I can get a working FF-10 from my source.


Top
 Profile  
 
 Post subject:
PostPosted: Apr Thu 07, 2011 9:15 pm 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
troydog wrote:
how big is the flat belt?

The drive motor to capstan belt measures 1/4" wide by 1.0 mm. thick by 27 mm. (10 3/4") in circumference. A new belt should probably be a bit smaller since this one is stretched a bit. Does this sound like something you might have? That would be great.

I could also use the other drive belt from the capstan to the sub-capstan but I haven't measured its circumference yet. I know it's the same height and width though.


Top
 Profile  
 
 Post subject:
PostPosted: Apr Fri 08, 2011 12:04 am 
Member

Joined: Oct Tue 26, 2010 1:59 am
Posts: 376
Location: 42025
I think the large one is about 9 inches a little over heck can not find the tape measure. lol they are about 1/4 wide black belts.

You want them you can have them for free just send me your mail addy an I will mail them. Heck they do not weight anything so shipping is no big deal.


Top
 Profile  
 
 Post subject:
PostPosted: Apr Fri 08, 2011 5:42 am 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
9" might be a bit small, but I also need the capstan to sub-capstan belt and that one is about half the size of the main belt. And you can't argue with free :) So thanks for the kind offer - PM sent.


Top
 Profile  
 
 Post subject:
PostPosted: Apr Fri 08, 2011 10:05 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
Well Michele, you are in luck. I was procrastinating on doing power electronics homework so I laid out a PCB to replace your bad FF10. A picture of the layout is below along with a link to the actual layout file. It can be opened using ExpressPCB available at http://www.expresspcb.com. Since they are small I will include them on a larger PCB that I am ordering anyway for negligible additional cost.

The board is the same size as the original part - 7/8" x 5/8". You could probably shave it down to fit inside of the orange package, or dip in it green paint to make it look just like the others. I will leave that step up to you.

Parts List:
Transistors: MMBT2222A
Diodes: CD0603-S01575
Resistors: Standard 0603 SMT. The values may have to be tweaked to get the bias point right for the transistors but they should be close to the schematic.
Capacitors: Standard 0603 SMT multilayer ceramic.

Board Image:
Image

Layout File:
http://dasarodesigns.com/~medasaro/6540%20ROM%20Adapter%20and%20FF10.pcb

Once you give me the go ahead, I will order the parts and can ship you a board to test in a week or so.

-Matthew

_________________
If it ain't broken, you’re not trying hard enough...


Last edited by 7jp4-guy on Apr Sat 09, 2011 9:14 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject:
PostPosted: Apr Sat 09, 2011 12:51 am 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
Holy moly!!! Are you kidding me? That has to be the most amazing piece of work I've ever seen. I'm serious - that's really incredible. You now officially have my nomination for ARF Member of the Year.

That is one impressive feat of design and engineering, let me tell you. Wow. How can I say no to an offer like that? Of course, I'd be delighted to see one of these That is just too cool.

Serously, I get a headache just looking at the schematic for that FF-10, trying to follow the pretzel-like signal path in there. I am just speechless that you were able to translate that so cleanly and elegantly into a PCB that even has the original form factor. My hat's off to you!

My only question is that I don't see the two caps from the schematic in there. I'll freely admit I have no idea what they're for but they must serve some purpose. Tming? Filtering? Any ideas?

Anyway, this is above and beyond the call of duty. What more can I say? Thanks! :D :D :D


Top
 Profile  
 
 Post subject:
PostPosted: Apr Sat 09, 2011 9:14 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
You are certainly welcome. I had a lot of fun making it and I will order the boards today. I forgot the include the capacitors in the parts list but I edited it so they are there now - they were always in the design of the board.

Please note that even through I posted the design file I still retain the copyright to the boards - you are welcome to make them for yourself, but please don't sell them without my permission.

-Matthew

P.S. Having a bachelors degree in electrical engineering and being at MIT working on a masters degree really helps with projects like these...

_________________
If it ain't broken, you’re not trying hard enough...


Last edited by 7jp4-guy on Apr Sat 09, 2011 9:53 pm, edited 2 times in total.

Top
 Profile  
 
 Post subject:
PostPosted: Apr Sat 09, 2011 9:49 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
The boards and parts are ordered. I will get them next week and post when I do.

-Matthew

_________________
If it ain't broken, you’re not trying hard enough...


Top
 Profile  
 
 Post subject:
PostPosted: Apr Sat 09, 2011 10:21 pm 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
Wow, thanks again ever so much. I'll be more than happy to credit you whenever the topic comes up and I have absolutely no desire to make copies. I think one or two of them should be about a lifetime supply for me :) However, since this thread is now on the web, you might eventually get inquiries from other people. The FF-10 was not the most reliable part of the VT-100 series.

I can appreciate the work behind it too because I designed a little VLSI circuit back in the days of 5 micron design rules and it was a pain in the butt.


Top
 Profile  
 
 Post subject:
PostPosted: Apr Sat 09, 2011 10:31 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
Oh. I forgot to mention. The reason that I want to retain copyright is that I am going to sell the extras on eBay. (I will get 15 of them in the board order.) Don't worry though, I will give you as many as you need for free since you gave me the idea, schematics, and dimensions. 8)

-Matthew D'Asaro

_________________
If it ain't broken, you’re not trying hard enough...


Top
 Profile  
 
 Post subject:
PostPosted: Apr Sun 10, 2011 9:42 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 11017
Location: Omak,wa,usa
Hello Matthew,
I also down loaded that pcb program.
I will make lot easier then drawing it by hand on my drafting table.

That is a nicew layout on your board

Rich
P.S. Michele Wow I sure glad these you guys like Matthew trying to care on some of these old sets it's to great to the younger crowd keep this hobby alive


Top
 Profile  
 
 Post subject:
PostPosted: Apr Sun 10, 2011 10:14 pm 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
I'll definitely second that. Without Matthew's board, this project would be dead in the water. I'm really looking forward to getting my custom repro FF-10 :)


Top
 Profile  
 
 Post subject:
PostPosted: Apr Sun 10, 2011 10:25 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
Another question. What voltage does pin 3 of the FF10 sit at? Clearly pin 3 is Vcc and pin 6 is Vee, but to test my replacements accurately I will need to know what voltage Vee is supposed to be at and I couldn't obviously find that info on the schematic.

-Matthew

_________________
If it ain't broken, you’re not trying hard enough...


Last edited by 7jp4-guy on Apr Mon 11, 2011 1:33 am, edited 1 time in total.

Top
 Profile  
 
 Post subject:
PostPosted: Apr Mon 11, 2011 12:58 am 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
"What voltage does pin of the FF10 sit at?"

Well I hope the number of the pin you were asking about was "2", because the answer to that is 4.3 v. The signal on this pin is a square wave that is 8.5 v. P-P. Vcc (pin 3) is 9 v. Pin 6 is ground. I measured a 2.5 v. P-P signal at pins 1 and 5.

Here is the schematic of the FF-10 we're talking about. My earlier post showed IC 6008 which is another FF-10. There are three of these things on the servo board.

Image


Top
 Profile  
 
 Post subject:
PostPosted: Apr Mon 11, 2011 1:33 am 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
Thanks and sorry about the typo (now fixed.) It is pin 3 which I need to know. 9V it is!

-Matthew

_________________
If it ain't broken, you’re not trying hard enough...


Top
 Profile  
 
 Post subject:
PostPosted: Apr Mon 11, 2011 3:01 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5337
Location: Ann Arbor, MI
Michele wrote:
Well I hope the number of the pin you were asking about was "2", because the answer to that is 4.3 v. The signal on this pin is a square wave that is 8.5 v. P-P.

Ha! If you put a DC reading voltmeter on a signal that is a 8.5 V P-P square wave, the meter would measure it as 4.3 volts. I suppose that the reading is even sort of useful.

_________________
Tom


Top
 Profile  
 
 Post subject:
PostPosted: Apr Mon 11, 2011 6:03 am 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
Yeah, I guess the full version of what I meant to say is:

"The schematic has a little 4.3 v. printed next to that pin. When I put a scope (which I usually keep in AC coupling because I'm looking at AC signals) on it I got 8.5 v. P-P. So our two data points are basically in agreement".


Top
 Profile  
 
 Post subject:
PostPosted: Apr Fri 15, 2011 5:41 am 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
I finally have all the parts to make the FF-10s and I hope to get in done in a couple of days. Lots of work / school though so it might be a bit longer than that. I will keep you all up to date.

-Matthew

_________________
If it ain't broken, you’re not trying hard enough...


Top
 Profile  
 
 Post subject:
PostPosted: Apr Fri 15, 2011 6:51 am 
Member

Joined: Apr Sun 05, 2009 9:48 pm
Posts: 614
Location: Planet Claire
Awesome! It's just sitting on the bench waiting. Obviously your priorities come first, but let me know when you've got a prototype.

In the meantime, I received a bunch of belts that troydog kindly contributed to the project and one of them fit the motor to capstan drive perfectly, so now we have a new belt there.


Top
 Profile  
 
 Post subject:
PostPosted: Apr Mon 18, 2011 1:40 am 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2219
Location: Seattle, WA, USA
Well, I think I have it working! :D I populated the board and it worked on the first try. I was amazed - nothing is that easy.

Image

Above is the breadboard that I used for the test. The chip is a 74LS04 inverter which is there so that I can make S and R always be in opposite states. After a quick static test to verify that the circuit retains its state, I applied a square-wave from my new (as of today) HP 8111A function generator to R and to the inverter input with the output of the inverter connected to S. I then connected one channel of the oscilloscope to Q and the other to Q!. With the function generator set to 10KHz and the oscilloscope set to 50us/div I get the following waveform.

Image

I set the oscilloscope to 2us/div and measured the rise-time to be about ~2uS. Below is a picture of that measurement.

Image

This all looks O.K. to me, but the only true test will be how it performs in circuit.

Finally, here are pictures of the front and back of the finished product.

Image

I dubbed this the FF10-MED since my full name is Matthew Eric D'Asaro.

-Matthew

Image

I should be able to ship tomorrow.

-Matthew D'Asaro

_________________
If it ain't broken, you’re not trying hard enough...


Last edited by 7jp4-guy on Apr Mon 18, 2011 7:35 pm, edited 1 time in total.

Top
 Profile  
 
Post New Topic Post Reply  [ 205 posts ]  Moderators: Mr. Detrola, 7jp4-guy Go to page Previous  1, 2, 3, 4, 5, 6 ... 11  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 12 guests



Search for:
Jump to:  
cron


































-->


Privacy Policy :: Powered by phpBB